. Animal flight; a record of observation . before perching there is an increase of the angle of incidence due to advancing ofthe wings. This is ordinary stop descent, with its usual rapid loss of speed. Rarely this stopdescent produces a slight and temporary gain of height. That is to say in numerous observa-tions it was found that the gliding of the large egret resembles that of herons, and differsfrom that of birds with a vulturine wing section. I have made similar observations in thecase of the Pond Heron (Ardeola grayi). 352 ANIMAL FLIGHT. Thus the study of the wing section suggests thatth
. Animal flight; a record of observation . before perching there is an increase of the angle of incidence due to advancing ofthe wings. This is ordinary stop descent, with its usual rapid loss of speed. Rarely this stopdescent produces a slight and temporary gain of height. That is to say in numerous observa-tions it was found that the gliding of the large egret resembles that of herons, and differsfrom that of birds with a vulturine wing section. I have made similar observations in thecase of the Pond Heron (Ardeola grayi). 352 ANIMAL FLIGHT. Thus the study of the wing section suggests thatthe Blue Heron is a bird with a good gliding in my observations of the bird in flight goesagainst this view. If the Blue Heron has a good gliding angle, andif soaring flight is due to the bird being lifted by someunknown upward trend in the wind, then the BlueHeron ought to be able to soar. The power of soaringflight has been ascribed to the Heron by one or twoobservers. It is a matter in which further observationis Wing section 01 Dusky Horned Owl (Urrua coromanda), takenmidway between carpal and elbow joints. D, D. Down shown with dotted T, P. Tensor patagii tendon. outline. Q. Shaft of secondary quill. M. Muscle. R. Radius. A. Air sac. U. Ulna. Fig. 87 is a section of the wing of the DuskyHorned Owl (Urrua coromanda). The span of thespecimen from which this section was made was 55 loading was .88 lb. per square foot. I obtained avery similar wing section from another owl, namely,the Spotted Owlet (Athene brama), having a loading lb. per square foot. The slenderness of the wing section suggests thatthe owl has a good gliding angle. On one or perhaps twooccasions I have seen a large owl gliding in calm airwith what appeared to me to be a surprisingly smallloss of height. Probably this impression was producedon me because, at the time, I was studying the flight ANIMAL FLIGHT. 353 of Flying-foxes {Pteropus). These bats glide witha well-marked l
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